Strings in holes?
Strings in holes?
Hello fellow withprinters. Whats happening here? Stringing is not the problem, if i print string tests, they are good. Its only in holes, the walls wont stick. Any suggestions for a fix?
Edit: Found the problem. The temperature sensor was faulty. Changed it and now everything is fine.
This is somewhat normal for FDM 3D printing. It's a known behavior of filament in its molten state on the interior walls. As the nozzle goes around, it's always at a tangent to previously laid filament, and can have the effect of pulling just-laid filament off of its bedding into the previous layer.
It's one of those things that to fully understand I'd have to find one of the dissertations one of the community members did.
But with marlin firmware (using klipper right now) it worked...
Edit: Black is Marlin, white is klipper.
Different filaments will print differently, so it might not be the firmware
Doesn't look like the same gcode though. Initial layer lines are facing opposite directions. You also have small brown inclusions in the white one, which is usually the result of burning/dripping filament from a leak.
The problem is that the length of wall inside the holes is so short that the filament hasn't firmed up very much before the nozzle finishes the wall path and then pulls away from it.
Your first, best option is to slow down the print speed for just the exterior walls to give the filament a little more time to harden. Whatever the current speed is, cut it in half.
If your slicer doesn't have that much specificity in the settings, slow down all wall printing (or try a better slicer like OrcaSlicer or SuperSlicer).
Thanks, will look into that.
Potential solutions:
- Coasting/Wiping before travel
- Linear Advance
- Tuning retraction
- Or completely side-step the issue by turning on "Avoid crossing perimeters"
The last one should really be default-activated. It avoids so much stringing and ugly outside surfaces.
This isn't stringing though. It's the outter perimeter that is getting partially pulled away from the print. If you look at the second picture on the bottom hole, there is more visible looping of the filament. Circle perimeters generally print in circles with consistent start and end points without the need to cross across a void like that.
Printing inner perimeters first may help here without having to do extrusion tweaking. If that isn't the problem, slowing down perimeters (or the entire print) will give the layer more time to bond.
However, there could be a mechanical issue starting to show as well. If there is slop in one direction and not the other, a belt gear on the stepper could be getting loose. It's something to check, anyway.
But if you enable "Avoid crossing perimeters" this problem will still not occur.
Since OP mentioned a switch from Marlin to Klipper, it could also be acceleration settings or something like it.
Kind of looks like the wall isn't adhearing to layer below it and the nozzle is pulling it around
Correct. How do i fix it?
Print a bit hotter and a bit slower to improve layer adhesion
You could try turning up your extrusion and temp a little bit. Pushing more material should give added smoosh and better adhesion. I'd make a small model with the same feature I'm having trouble with to test settings with, then try the whole print with the new settings and cross my fingers.
In your second picture is your print upside down/bottom layer facing up? If yes, that's "normal" slicer behavior for round things that end. You can trick your slicer into making those bridges by adding a 0.2mm high bridge - just make sure that it doesn't touch the two walls and your slicer will generally not print floating perimeters. You can test this theory by looking at the sliced preview in your slicer.
I think ot looks ok. Font know how to add bridges in the slicer. Its not my design so i only have the .stls
What do you see in the preview in the slicer?
I bet those are movements across one part of the print to the other and for some reason it isn’t retracting enough before the movements.
Although you’d see some heavy stringing on a retraction tower test most likely if it’s that bad.
May be fixed with something like wall order or wipe during infill
Nope, it should be walls. They just wont stick. How does wipe during infill work? cant find anything in cura or google. I try changing the wall order now, thanks for the tip, could work.
Try the "combing" setting "with infill" should drag the nozzle across the infill to wipe any strings away. Be careful with this though as I've had it knock prints loose from the bed. This print looks to have a large adhesion surface so it shouldn't be an issue.